The present invention relates to an electrolytic solution containing a nonaqueous solvent and an electrolyte salt, a secondary battery using the same, a battery pack using the same, an electronic device using the same, and an electrical vehicle using the same.
In recent years, electronic devices represented by a portable terminal or the like have been widely used, and it is strongly demanded to reduce their size and weight and to achieve their long life. Accordingly, as a power source, a battery, in particular, a small and light-weight secondary battery capable of providing a high energy density has been developed. In these days, it has been considered to apply such a secondary battery not only to the electronic devices but also to a power source such as a battery pack, an electrical vehicle such as an electrical automobile, or the like.
For the secondary battery, it has been considered to use various elements as a carrier (matter entering and leaving a cathode and an anode at the time of charge and discharge). Specially, a lithium secondary battery using lithium as a carrier (using lithium reaction as charge and discharge reaction) is largely prospective, since such a lithium secondary battery provides a higher energy density than a lead battery and a nickel cadmium battery. The lithium secondary battery includes a lithium ion secondary battery using insertion and extraction of lithium ions and a lithium metal secondary battery using precipitation and dissolution of lithium metal.
The secondary battery includes a cathode, an anode, and an electrolytic solution. The electrolytic solution contains a nonaqueous solvent and an electrolyte salt. The electrolytic solution functioning as a medium for charge and discharge reaction largely affects performance of the secondary battery. Thus, various studies have been made on the composition thereof.
Specifically, to improve high temperature characteristics, a dicarbonic ester compound, a dicarboxylic compound, or a disulfonic compound is used (for example, see Patent document 1). To improve durable years and performance by improving ion conductivity, tetrakisfluoroalkyl borate or fluoroalkylphosphate is used (for example, see Patent documents 2 and 3). To improve performance, a lithium salt such as Li[N(SO2F)2] is used (for example, see Patent document 4). To improve high temperature conservation characteristics and cycle characteristics, lithium phosphate difluoride is used (for example, see Patent document 5).
Further, to improve swollenness characteristics in the high temperature environment, initial charge and discharge characteristics, and the like, a spirodilactone compound such as 1,6-dioxaspiro[4,4]nonane-2,7-dione is used (for example, see Patent documents 6 to 9).
Specifically, to improve cycle characteristics, a spiro dry compound or a dioxane compound is used as an electrode stabilizing addition agent (for example, see Patent document 10). To improve high temperature conservation characteristics and cycle characteristics, a dicarbonic ester compound is used (for example, see Patent document 11). In this case, as other auxiliary agent, tetraoxaspiro[5,5]undecane or the like is used.